This invention is concerned with decoding digital information stored on a magnetic tape. Digital information such as a sequence of "ones" and "zeroes" may be encoded on a magnetic tape by utilizing a physical distance between magnetic flux transitions. Thus a "zero" may be represented by a "short" distance and a "one" may be represented by "long" distance between flux transitions. To retrieve or decode the stored information some method is required to distinguish between the "short" and "long" distances. One straightforward decoding method is to measure the time elapsed between successive flux transitions and compare the elapsed time to a reference time. "Short" and "long" distances may then be defined as corresponding to time intervals less than or greater than the known reference time respectively. However, for many systems variations in tape speed create difficulties with this approach. Because of the speed variations it is necessary that the "long" distance be sufficiently greater than the "short" distance that the corresponding "long" and "short" time intervals will be assured to be greater than or less than the fixed reference time under conditions of the maximum expected speed variations. Spacing of the information to allow for these conditions reduces the total amount of digital information that may be stored on a given length of tape.